Typical servers and storage products are usually built on a backplane card structure. Interconnection bays are provided for disk drives, controllers, communication cards, and other plug-in modules. A few types of backplane cards depend on high density connectors with polarizing pins and guide pins to assure the proper connection of modules.
One type of conventional polarizing pin is D-shaped, and several of these can be arranged in unique combinations simply by changing the orientations of the D-shaped pins and holes. The worth of this is limited to cases where the same size and types of connectors are used throughout a system. No advantage is provided in case of wrong combinations where different sizes and types of connectors are used, and such connectors and systems can be damaged if a wrong connection is attempted by mistake. Upside down installation of modules installed into the system's bays is also a source of trouble.
What is needed is a connector system that has its unique keying mechanism against any wrong connection or operation, and that can protect products from any damages of connectors and systems. This keying mechanism should be simple and inexpensive, and not degrade in operability. It should be widely applicable to any size/type of connectors being used on backplane card structure and modules.